This invention relates to sewing machines and is concerned particularly, but not exclusively, with sewing machines of the kind sometimes known as "cup overseaming machines" used to sew such materials as fur, skins and pelts (both natural and synthetic), felt, carpeting, plastics and knitwear.
The lubrication of the internal mechanisms of sewing machines can present problems. If it must be done manually by the operator, for example employing a drip feed from a pre-filled reservoir, the quantities of oil required at many locations may necessitate frequent fillings. Such an arrangement is very susceptible to human error, particularly as the operator may not have any special mechanical knowledge or skills and in industrial use it is frequently impossible without elaborate precautions to ensure that the lubrication is maintained.
This difficulty can of course be obviated by a forced feed of lubrication from a motor-driven pump, using mist lubrication techniques for example, but such a solution calls for complex and expensive mechanical adaptation and would be justified only in high-speed machines where there is a specific need for a high rate of circulation of lubricating fluid.
The present invention provides a means of lubrication that feeds the fluid intermittently but automatically, so that lubrication failure through operator error can be avoided, while at the same time said means are of a form that can be incorporated in a sewing machine in a more economical manner than a motor-driven forced feed lubrication system.